6.5 Specialty Slide Rules

While the majority of slide rules consisted of logarithmic scales for performing general calculations, many were designed for specific computations for very specific tasks. Just as a modern computer program might be used to perform a repeated calculation rather than typing in a series of similar computations again and again on an electronic calculator, special slide rules were developed for repeated calculations such as those found in the fields of electricity and electronics, chemistry, surveying, and so forth. Below are lists of slide rules that may be considered specialty rules in that they have scales specifically designed for use in a particular application or for a particular profession. Approximately 13% of the slide rules in the collection – 39 in total – are specialty rules.

The size Lx listed in these tables is the length in inches of the item’s greatest dimension, and not necessarily the length of a scale’s decade.

Aviation Slide Rules

Maker Model Year Type Lx Note
Felsenthal AN 5837-1 1943 C 8 Altitude Correction Computer; B/W main spiral scale, with fluorescent markings; WWII
Felsenthal D-4 1944 C 4 Time Distance Computer Type D-4; WWII device; Property of U.S. Army Air Forces; fluorescent numbers on black background
Felsenthal FAA-95 1950-1955 C 8 MB-1 Computer, Air Navigation, True Airspeed and Altitude; true altitude correction spiral on back
Felsenthal Dial-A-Con 1968 C 7 Flight computer, Type E6B, with instruction manual (by A. Fuchs), and vinyl case

Chemical Slide Rules

Maker Model Year Type Lx Note
Nestler 33 Chemiker 1924-1933 L 10 Early Chemical Rule, Albert Nestler A.G. LAHRi/B D.R. Patent Germany; Pickworth Data Slip on back; wide 1-line cursor
Hemmi 257 1956 L 10 Chemical Engineering; owner Frank Banks of CA

Electro and Electronics Slide Rules

Maker Model Year Type Lx Note
K&E 4133 1913-1922 L 8 Roylance Electrical Slide Rule, mahogany, early release; prod mark 255; used and in poor condition; missing original 3-hairline cursor
Faber-Castell 379 1923 L 5 Electro rule; nice condition; pearwood; Made in Bavaria and date marks 3 and 12 on back; V and Eff scales in well; W gauge on C
Hemmi 80/3
1935 L 10 Electro; tables on back and text on box in French
K&E N4133 1944 L 8 Roylance Electrical Slide Rule, mahogany; 3-hairline cursor; scale set #3; original case and box
K&E 4139 1946 L 10 Cooke Radio Slide Rule; Case: Polyphase Duplex DeciTrig 4071-3S
Pickett N-515-T 1958-62 L 10 Electronics model; leather case, strap – great condition; Cleveland Institute of Electronics
Pickett N-515-T 1958-62 L 10 Electronic; basically new-in-box; leather case, strap – great condition; Cleveland Institute of Electronics
Concise 380
1959-1966 C 4 Radio Computer, with instruction sheet; Concise Co., Ltd. 

Engraving/Proportions Slide Rules

Maker Model Year Type Lx Note
P.A.S. Co.  Engraving Rule
1928 L 7 Engraving Proportion Scale; sold by Art Brown & Bro. Inc. NewYork; similar to Hyde Optical Slide Rule at ISRM
Lawrence 10-C 1935-1938 L 5 Lawrence Engravers / Photographers Proportion Calculator; Wabash, IN
noID Engraving Rule
1940 L 20 18 inch proportions rule, perhaps used in printing, engraving; maker? American Blueprint? (similar construction to U.S. Military Rule); A/B scales range from 1 to 30, 12 inches from 1 to 10
Lawrence 10-N
1946 L 10 Lawrence Printer’s Proportion Rule; Peru, IN
C-Thru PS-79
1970 C 6 Proportional Scale, from the estate of Johnny Craig, noted comic book artist

Military Slide Rules

Maker Model Year Type Lx Note
Richardson Model of 1917 1917-1918 L 18 WW I military slide rule for ranging calculations; mahogany on brass; described in Richardson’s Slide Rule Simplified, 6th Ed.; made for J.H. Weil & Co., Phila.
Sillcocks-Miller M1 Slide Rule No. 547 1942 C 12 Military ballistic slide rule; angles in mils (800 mils = 45 deg); designed by Robert Crichlow
American Blueprint Military 1948-1957 L 12 US Military slide rule, for field artillery problems
Pickett 14 1958-1962 L 10 U.S. military rule; well-worn leather case

Spring Design Slide Rules

Maker Model Year Type Lx Note
Sandish Spring Calculator
1940 L 20 apparent home-made dual-slide spring calculation slide rule; traced by F. Sandish; original owner M.L. Rowe
Baetzmann Spring Calculator 1941 L 17 Spring Load Calculations slide rule; large format 17 in x 2.5 in x 0.75 in; two slides on front, one on back; owner (maker?) R. K. Baetzmann, 1941
J.B. Carroll Associated Spring M110 1952 L 10 early version, made for Associated Spring; no cursor
Acu-Rule Connecticut Spring 1955 L 10 Spring design calculations rule,version 3, made for Connecticut Spring Corp. 

Stadia (Surveying) Slide Rules

Maker Model Year Type Lx Note
Kolesch 2713 Stadia 1905-1911 L 10 stadia rule, 360deg, D.R.Patent No. 173660, likely made by Nestler; advertised in 1907 How to use Slide Rules; suede leather case; owner Everett Gowty, Perry, OK
K&E 4100 1915-1922 L 10 Stadia rule, early model, for use in surveying; instructions on back; all-glass cursor; prod marks 268 on end
K&E N4100 1938 L 10 Stadia rule, for use in surveying; instructions on back; metal rimmed cursor
Aristo 958 1970 L 10 Geodat 400g stadia rule; instructions (German), clip-on supports; 5-hairline cursor; box and 1364 insert

Weight Calculation Slide Rules

Maker Model Year Type Lx Note
Novotni Weight Calculator
1935 L 15 Novotni, but not marked as such; 13 inch o/a length; By-Products Steel Corporation; Commercial Trust Building, Philadelphia, Pa.
Pickett N-550-T 1962 L 10 Warren-Knight Weight Rule 1373-ET; Label Style 3 with copyright 1962

Other Specialty Slide Rules

Maker Model Year Type Lx Note
Richardson GE Analizer
1918 L 18 General Electric Company Quantity Analizer; similar construction to Richardson/J.H.Weil Slide Rule of 1917; slots apparently for cursor on edges
Acu-Rule Arel G-W Photo 1946 L 10 Goodchild-Whitney (G-W) Photo Slide Rule, with instruction book
Lawrence 10-D
1946 L 10 Lawrence Lumber Calculator; Peru, IN
Blundell Rules Limited Radiac No. 1 1952-1956 C 5 radiation exposure calculator; log log scales; reversible land/sea discs; instructions on back
Pickett N1040-ES 1954 L 10 Fisher Control Valve Sizing Rule; made for Fisher Governor Co, Marshalltown, Iowa
Kahl Scientific Culbertson Slide Rule 1955 C 8 Temperature, Depth, Salinity calcs; Designed by Margaret Culbertson for the U.S. Navy Electronics Lab; full instructions

Below is a histogram of Specialty Slide Rules in the Collection as distributed over the decades of the 20th Century: